JP2006053361A - Optical system having a plurality of optical elements and image pickup device provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical system which is effectively made small-sized and light in weight, and is fabricated at a low cost, and also to provide an image pickup device provided with the optical system. <P>SOLUTION: The image pickup device is composed of: the optical system provided with a plurality of optical elements having a finite refractive power; and electronic image pickup elements arranged on the image side of the optical system. Therein, at least one of a plurality of the optical elements is made of plastic and IR cut coating is applied on at least one surface r<SB>9</SB>of the optical elements made of plastic. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical system having a plurality of optical elements and an image pickup apparatus including the same, and for example, an optical system having a plurality of optical elements such as a lens member and a prism, a digital camera including the same, and an image pickup module for a mobile phone And the like. More specifically, the present invention relates to an optical system in which an infrared cut coat is applied to a refracting surface of an optical element, and an imaging apparatus including the same.

  In recent years, digital cameras (electronic cameras) have attracted attention as next-generation cameras that replace silver salt 35 mm film (commonly known as Leica version) cameras. Furthermore, it is being considered for use in a wide range from a high-functional type for business use to a portable popular type. The mobile phone also has a built-in imaging module, so you can easily enjoy commemorative photography.

  In these digital cameras and mobile phone imaging modules, CCDs, CMOSs, and the like are used as imaging elements.

  An image pickup device such as a CCD or CMOS has high sensitivity even in a region where the wavelength is longer than the visible region (generally, it is said that the wavelength is about 380 nm to about 780 nm), so-called infrared region. The received infrared rays cause a decrease in resolution and image degradation. For this reason, an imaging apparatus such as a camera using an imaging element such as a CCD or CMOS requires an infrared cut filter that removes infrared rays.

  In general, the transmittance characteristic of an infrared cut filter is designed so that the transmittance at a wavelength of about 780 nm or more is zero as much as possible.

  There are two types of infrared cut filters: the absorption type in which the filter material itself absorbs infrared rays, and the reflective type in which the filter surface is coated with an infrared cut coat that cuts infrared rays. In an imaging device such as a digital camera or video camera, However, a filter having one or both properties is disposed between the photographing lens and the image sensor.

  Examples of the infrared cut coating method include a vacuum deposition method and a sputtering method. The vacuum evaporation method is a method of forming a thin film by evaporating a vapor deposition material in a high vacuum and depositing the evaporation material on a substrate. On the other hand, the sputtering method is a method in which a thin film is formed by depositing on the substrate atoms that have been knocked out by colliding high-energy atoms or molecules with a vapor deposition substance (target).

  By the way, in the case of arranging an infrared cut filter as described above, whether it is an absorption type or a reflection type, in order to ensure the physical strength of the filter itself, a thickness of at least about 0.5 mm should be secured. Must-have. Furthermore, there is a problem that the entire length of the optical system becomes long because it is necessary to keep a certain distance from the lens before and after the filter.

  In addition, since the infrared cut filter itself is arranged separately from the optical system, the cost is increased accordingly.

Patent Documents 1 and 2 describe that in order to solve these problems, miniaturization is achieved by applying an infrared cut coat of a multilayer film to any one lens surface in the optical system of the camera. Has been. Patent Document 3 describes that an infrared cut coat is deposited on the lens surface of a single lens.
JP-A-5-207350 JP 2002-277738 A JP 2004-88181 A JP 2004-139035 A

  In recent years, it has been required to manufacture imaging devices such as digital cameras and video cameras as cheaply as possible products. For this reason, it is essential to reduce the cost of the optical system as much as possible. Patent Document 4 describes that a film forming cost is reduced by collectively applying an infrared cut coat to any one of a large number of glass plano-convex lenses.

  In addition, with the downsizing of imaging devices such as digital cameras and video cameras, there is an increasing demand for weight reduction.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide an optical system that is effective for downsizing and weight reduction and can be manufactured at low cost, and an imaging apparatus including the optical system. is there.

In order to achieve the above object, an imaging apparatus according to the present invention includes an optical system including a plurality of optical elements having finite refractive power, and an electronic imaging element disposed on the image side of the optical system.
At least one of the plurality of optical elements is made of plastic, and an infrared cut coat is applied to at least one surface of the optical element made of plastic.

Further, the optical system having a plurality of optical elements of the present invention is an optical system including an optical element having a finite refractive power,
At least one of the plurality of optical elements is made of plastic, and an infrared cut coat is applied to at least one surface of the optical element made of plastic.

  In the present invention, an optical element having a refractive power is defined as an optical element having a refractive power other than zero in any effective plane of the optical element.

  Below, the reason and effect | action which take the said structure in this invention are demonstrated.

  According to the optical system of the present invention, since at least one of the plurality of optical elements is made of plastic, the entire optical system can be reduced in weight, and the imaging apparatus or the like using the same can be reduced in weight and size. It is effective for.

  Furthermore, since an optical element made of plastic can be manufactured at a lower cost than an optical element made of glass, the manufacturing cost of an optical product, an imaging device, and the like can be suppressed. Moreover, since plastic is easier to mold than glass, it is possible to easily manufacture an optical element (for example, a lens member) having a desired shape.

  Furthermore, in the imaging apparatus or optical system of the present invention, it is preferable that the infrared cut coat is applied to a plurality of refractive surfaces including one surface of an optical element made of plastic. Thereby, the variation in the film thickness of each infrared cut coat can be reduced, the occurrence of defective products can be reduced, and it is effective in improving the yield and reducing the cost.

  If the number of layers on one refractive surface is small, the time required for the coating process can be shortened, and the temperature rise of the optical element in the coating process can be suppressed. As a result, it is possible to prevent the deformation of the optical element made of plastic due to a temperature rise, and it is difficult for the imaging performance to deteriorate due to the deterioration of surface accuracy.

  More preferably, the transmittance of the entire optical system is 10% or less of the average value of transmittance at wavelengths of 500 nm to 550 nm over a wavelength range of 750 nm to 850 nm.

  Further, the plastic material used as the optical element of the present invention has a heat deformation temperature in the range of 100 ° C to 130 ° C. The refractive index is in the range of 1.45 to 1.65, and the Abbe number is in the range of 20 to 60.

  According to the imaging apparatus and the optical system of the present invention, at least one of the plurality of optical elements in the optical system is made of plastic, and an infrared cut coat is formed on at least one surface of the optical element made of plastic. As a result, the entire optical system can be reduced in weight. That is, it is effective for reducing the weight and size of an imaging apparatus using the same.

  Furthermore, since an optical element made of plastic can be manufactured at a lower cost than an optical element made of glass, the manufacturing cost of an optical product, an imaging device, and the like can be suppressed. Moreover, since plastic is easier to mold than glass, it is possible to easily manufacture an optical element (for example, a lens member) having a desired shape.

  Examples 1 to 5 of the optical system used in the present invention will be described below.

  FIG. 1 is a lens cross-sectional view of the zoom lens system of Examples 1 and 2 at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity. FIG. 2 is a lens cross-sectional view of the zoom lens system at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity. FIG. 3 shows a lens cross-sectional view of the imaging lens system of Example 5 when focusing on an object point at infinity.

  1 and 2, the first lens group is indicated by G1, the aperture stop is indicated by S, the second lens group is indicated by G2, the third lens group is indicated by G3, the cover glass of the electronic image pickup element is indicated by CG, and the image plane is indicated by I. . In FIG. 3, the aperture stop is indicated by S, the first positive lens is indicated by L1, the second positive lens is indicated by L2, the third negative lens is indicated by L3, the cover glass of the electronic image pickup device is indicated by CG, and the image plane is indicated by I.

  As shown in FIG. 1, the zoom lens system of Embodiment 1 has negative refractive power in order from the object side, and has a first lens group G1, which includes a biconcave lens L11, an aperture stop S, and positive refractive power. The second lens group G2 includes a biconvex lens L21 and a biconcave lens L22, the third lens group G3 includes a biconvex lens L31 having a positive refractive power, and a cover glass CG.

  In this embodiment, the lenses in the first lens group G1 to the third lens group G3 are all made of plastic.

  During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves so as to be convex toward the image side in the vicinity of the telephoto end (that is, moves along a concave locus on the object side) and the second lens. The group G2 moves to the object side together with the aperture stop S. The third lens group G3 is fixed.

  Further, the aspherical surfaces are the both surfaces of the biconcave lens L11 of the first lens group G1, the both surfaces of the biconvex lens L21 of the second lens group G2, the image side surface of the biconcave lens L22 of the second lens group G2, and the third lens group. It is provided on the image side surface of the G3 biconvex lens L31.

  In Example 1, 44 layers of infrared cut coating on the image side surface (the ninth surface) of the biconvex lens L31 in the third lens group G3 are performed.

  The film configuration of the infrared cut coat applied to the ninth surface of the optical system of Example 1 is shown in Table 1 below in order from the substrate (that is, the lens surface) side. Further, the transmittance characteristics on the optical axis of the entire optical system of Example 1 are as shown in FIG.

  As shown in FIG. 4, in this embodiment, the desired wavelength characteristics can be obtained by cutting infrared rays well.

Table 1
──────────────────
Number of layers Film material Optical film thickness ──────────────────
1 TiO ₂ 0.2071 × λ / 4
2 SiO ₂ 0.395 × λ / 4
3 TiO ₂ 1.9539 × λ / 4
4 SiO ₂ 1.7543 × λ / 4
5 TiO ₂ 1.6061 × λ / 4
6 SiO ₂ 1.6097 × λ / 4
7 TiO ₂ 1.5417 × λ / 4
8 SiO ₂ 1.5714 × λ / 4
9 TiO ₂ 1.5146 × λ / 4
10 SiO ₂ 1.5589 × λ / 4
11 TiO ₂ 1.5051 × λ / 4
12 SiO ₂ 1.5563 × λ / 4
13 TiO ₂ 1.4976 × λ / 4
14 SiO ₂ 1.5567 × λ / 4
15 TiO ₂ 1.5026 × λ / 4
16 SiO ₂ 1.5647 × λ / 4
17 TiO ₂ 1.5137 × λ / 4
18 SiO ₂ 1.5811 × λ / 4
19 TiO ₂ 1.5388 × λ / 4
20 SiO ₂ 1.6133 × λ / 4
21 TiO ₂ 1.5979 × λ / 4
22 SiO ₂ 1.6941 × λ / 4
23 TiO ₂ 1.783 × λ / 4
24 SiO ₂ 1.9277 × λ / 4
25 TiO ₂ 1.9895 × λ / 4
26 SiO ₂ 2.0126 × λ / 4
27 TiO ₂ 2.0378 × λ / 4
28 SiO ₂ 2.0446 × λ / 4
29 TiO ₂ 2.062 × λ / 4
30 SiO ₂ 2.0531 × λ / 4
31 TiO ₂ 2.068 × λ / 4
32 SiO ₂ 2.0626 × λ / 4
33 TiO ₂ 2.069 × λ / 4
34 SiO ₂ 2.0591 × λ / 4
35 TiO ₂ 2.0707 × λ / 4
36 SiO ₂ 2.0552 × λ / 4
37 TiO ₂ 2.0612 × λ / 4
38 SiO ₂ 2.0468 × λ / 4
39 TiO ₂ 2.0475 × λ / 4
40 SiO ₂ 2.0273 × λ / 4
41 TiO ₂ 2.0072 × λ / 4
42 SiO ₂ 1.9692 × λ / 4
43 TiO ₂ 1.9273 × λ / 4
44 SiO ₂ 0.9515 × λ / 4
──────────────────
Note) λ = 500nm
.

  Since the zoom lens system of Example 2 has the same configuration as the zoom lens system of Example 1 described above except that the surface on which the infrared cut coat is applied is different, the description of the same configuration is omitted. To do.

  In Example 2, 22 layers of infrared cut coat are applied to each of the two surfaces of the object side surface (eighth surface) and the image side surface (9th surface) of the biconvex lens L31 in the third lens group G3.

  Table 2 shows the film configuration of the infrared cut coat applied to the eighth and ninth surfaces of the optical system of Example 2 in order from the substrate side. In addition, Table 3 shows incident angle data of the principal ray having the maximum image height in the wide-angle end focal length state of the optical system of Example 2, and a surface on which no infrared cut coat (IR coat) is applied. Table 4 shows the average values of the incident angles on the applied surface.

  The transmittance characteristics on any one of the eighth and ninth surfaces are as shown in FIG.

  Further, the transmittance characteristics on the optical axis of Example 2 by infrared cut coating on the two object side surfaces (eighth surface) and image side surface (ninth surface) of the biconvex lens L31 are as shown in FIG.

  As shown in FIG. 6, in this embodiment, desired wavelength characteristics can be obtained by cutting infrared rays well.

Table 2
──────────────────
Number of layers Film material Optical film thickness ──────────────────
1 TiO ₂ 0.181 × λ / 4
2 SiO ₂ 0.4108 × λ / 4
3 TiO ₂ 1.9224 × λ / 4
4 SiO ₂ 1.7824 × λ / 4
5 TiO ₂ 1.6345 × λ / 4
6 SiO ₂ 1.6908 × λ / 4
7 TiO ₂ 1.5826 × λ / 4
8 SiO ₂ 1.6646 × λ / 4
9 TiO ₂ 1.5763 × λ / 4
10 SiO ₂ 1.664 × λ / 4
11 TiO ₂ 1.6346 × λ / 4
12 SiO ₂ 1.7215 × λ / 4
13 TiO ₂ 1.8085 × λ / 4
14 SiO ₂ 1.9642 × λ / 4
15 TiO ₂ 2.0516 × λ / 4
16 SiO ₂ 2.0597 × λ / 4
17 TiO ₂ 2.0654 × λ / 4
18 SiO ₂ 2.0675 × λ / 4
19 TiO ₂ 2.0706 × λ / 4
20 SiO ₂ 2.0256 × λ / 4
21 TiO ₂ 1.9937 × λ / 4
22 SiO ₂ 1.0126 × λ / 4
──────────────────
Note) λ = 500nm
.

Table 3
─────────────────
Surface Incident angle (°) ─────────────────
r ₁ 51.5
r ₂ 0.8
r ₃
r ₄ 22.2
r ₅ 2.3
r ₆ 6.2
r ₇ 22.9
r ₈ 27.0 (IR coat)
r ₉ 7.1 (IR coat)
─────────────────
.

Table 4
──────────────────
Surface Incident angle average value (°) ──────────────────
IR-coated surface 17.7
IR coated surface 17.0
──────────────────
.

  As shown in FIG. 2, the zoom lens system of Example 3 has negative refractive power in order from the object side, and has a first lens group G1, which includes a biconcave lens L11, an aperture stop S, and positive refractive power. The second lens group G2 includes a biconvex lens L21 and a biconcave lens L22, the third lens group G3 includes a positive meniscus lens L31 having a positive refractive power and a convex surface facing the image side, and a cover glass CG. ing.

  In this embodiment, the biconvex lens L21 of the second lens group G2 is made of glass, but all other lenses are made of plastic.

  During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the image side so as to be convex toward the image side in the vicinity of the telephoto end (that is, moves along a concave locus on the object side). The second lens group G2 moves along with the aperture stop S toward the object side. The third lens group G3 is fixed.

  Further, the aspherical surfaces are the both surfaces of the biconcave lens L11 of the first lens group G1, the both surfaces of the biconvex lens L21 of the second lens group G2, the image side surface of the biconcave lens L22 of the second lens group G2, and the third lens group. It is provided on the image side surface of the G3 positive meniscus lens L31.

  In Example 3, the object side surface (fourth surface) of the biconvex lens L21 in the second lens group G2, the object side surface (sixth surface) of the biconcave lens L22, and the object side surface (first lens) of the positive meniscus lens L31 in the third lens group G3. 8 layers) and an image side surface (9th surface) are each provided with 6 layers of infrared cut coat. In this embodiment, even if the lens members are different from each other, the infrared cut coat is not applied to the opposing lens surfaces (for example, the fifth surface and the sixth surface). Thereby, generation | occurrence | production of a ghost etc. can be prevented.

  Table 5 shows the film configuration of the infrared cut coat applied to the fourth surface, the sixth surface, the eighth surface, and the ninth surface of the optical system of Example 3 in order from the substrate side. In addition, the incident angle data of each principal ray of the maximum image height in the wide-angle end focal length state of the optical system of Example 3 are shown in Table 6, and the surface on which the infrared cut coat is not applied and applied. Table 7 shows an average value of the incident angles to the surface.

  The transmittance characteristics on any one of the fourth surface, the sixth surface, the eighth surface, and the ninth surface are as shown in FIG.

  Further, the transmittance characteristics on the optical axis of the entire optical system of Example 3 are as shown in FIG.

  As shown in FIG. 8, in this embodiment, the desired wavelength characteristics can be obtained by cutting the infrared rays well.

Table 5
──────────────────
Number of layers Film material Optical film thickness ──────────────────
1 TiO ₂ 0.1398 × λ / 4
2 SiO ₂ 2.1496 × λ / 4
3 TiO ₂ 1.7933 × λ / 4
4 SiO ₂ 1.7406 × λ / 4
5 TiO ₂ 1.61 × λ / 4
6 SiO ₂ 0.8669 × λ / 4
──────────────────
Note) λ = 500nm
.

Table 6
─────────────────
Surface Incident angle (°) ─────────────────
r ₁ 46.8
r ₂ 3.6
r ₃
r ₄ 18.6 (IR coat)
r ₅ 5.6
r ₆ 7.9 (IR coat)
r ₇ 30.2
r ₈ 32.7 (IR coat)
r ₉ 4.1 (IR coat)
─────────────────
.

Table 7
──────────────────
Surface Incident angle average value (°) ──────────────────
IR coated surface 21.5
IR coated surface 15.9
──────────────────
.

  The zoom lens system of Example 4 has the same configuration as the zoom lens system of Example 3 described above except that the surface on which the infrared cut coat is applied is different. Therefore, the description of the same configuration is omitted. To do.

  In Example 4, a 22-layer infrared cut coat is applied to the object side surface (fourth surface) of the biconvex lens L21 in the second lens group G2, and the image side surface (ninth surface) of the positive meniscus lens L31 in the third lens group G3. Eight layers of infrared cut coat are applied.

  Table 8 shows the film configuration of the infrared cut coat applied to the fourth surface of the optical system of Example 4 in order from the substrate side. Table 9 shows the film configuration of the infrared cut coat applied to the ninth surface in order from the substrate side. In addition, the incident angle data on each surface of the principal ray having the maximum image height in the wide-angle end focal length state of the optical system of Example 4 are shown in Table 10, and the surface on which the infrared cut coat is not applied and on the surface. Table 11 shows an average value of the incident angles to the surface.

  The transmittance characteristic on one surface of the fourth surface is as shown in FIG. The transmittance characteristics on one surface of the ninth surface are as shown in FIG. Further, the transmittance characteristics on the optical axis of the entire optical system of Example 4 are as shown in FIG.

  As shown in FIG. 10, in this embodiment, desired wavelength characteristics can be obtained by cutting infrared rays well.

Table 8
──────────────────
Number of layers Film material Optical film thickness ──────────────────
1 TiO ₂ 0.181 × λ / 4
2 SiO ₂ 0.4108 × λ / 4
3 TiO ₂ 1.9224 × λ / 4
4 SiO ₂ 1.7824 × λ / 4
5 TiO ₂ 1.6345 × λ / 4
6 SiO ₂ 1.6908 × λ / 4
7 TiO ₂ 1.5826 × λ / 4
8 SiO ₂ 1.6646 × λ / 4
9 TiO ₂ 1.5763 × λ / 4
10 SiO ₂ 1.664 × λ / 4
11 TiO ₂ 1.6346 × λ / 4
12 SiO ₂ 1.7215 × λ / 4
13 TiO ₂ 1.8085 × λ / 4
14 SiO ₂ 1.9642 × λ / 4
15 TiO ₂ 2.0516 × λ / 4
16 SiO ₂ 2.0597 × λ / 4
17 TiO ₂ 2.0654 × λ / 4
18 SiO ₂ 2.0675 × λ / 4
19 TiO ₂ 2.0706 × λ / 4
20 SiO ₂ 2.0256 × λ / 4
21 TiO ₂ 1.9937 × λ / 4
22 SiO ₂ 1.0126 × λ / 4
──────────────────
Note) λ = 500nm
.

Table 9
──────────────────
Number of layers Film material Optical film thickness ──────────────────
1 TiO ₂ 0.1431 × λ / 4
2 SiO ₂ 2.0867 × λ / 4
3 TiO ₂ 1.7065 × λ / 4
4 SiO ₂ 1.6211 × λ / 4
5 TiO ₂ 1.5306 × λ / 4
6 SiO ₂ 1.6518 × λ / 4
7 TiO ₂ 1.5314 × λ / 4
8 SiO ₂ 0.8312 × λ / 4
──────────────────
Note) λ = 500nm
.

Table 10
─────────────────
Surface Incident angle (°) ─────────────────
r ₁ 46.8
r ₂ 3.6
r ₃
r ₄ 18.6 (IR coat)
r ₅ 5.6
r ₆ 7.9
r ₇ 30.2
r ₈ 32.7
r ₉ 4.1 (IR coat)
─────────────────
.

Table 11
──────────────────
Surface Incident angle average value (°) ──────────────────
IR-coated surface 21.1
IR coated surface 11.4
──────────────────
.

  As shown in FIG. 3, the imaging lens system of Example 5 includes, in order from the object side, an aperture stop S, a first positive meniscus lens L1 having an aspheric object side surface with a convex surface facing the object side, and a biconvex image surface. The lens includes a second aspherical second lens L2, a third concave negative aspherical lens L3, and a cover glass CG.

  In this embodiment, the first lens L1 to the third lens L3 are all made of plastic.

  The specifications of Example 5 are an optical system having a focal length f = 3.83 mm, an image height of 2.30 mm, an F number = 2.98, and a total angle of view 2ω = 63.0 °.

  In Example 5, 18 layers of infrared cut coating are applied to each of the two image side surfaces (fifth surface) of the second positive lens L2 and the image side surface (seventh surface) of the third negative lens L3. ing.

  Table 12 shows the film configuration of the infrared cut coat applied to the fifth surface and the seventh surface of the optical system of Example 5 in order from the substrate side. In addition, Table 13 shows incident angle data of the principal ray having the maximum image height in the optical system of Example 5 on each surface, and the incidence on the surface on which the infrared cut coat is not applied and on the surface on which the infrared ray is applied. Table 14 shows the average value of the corners.

  The transmittance characteristics on any one of the fifth surface and the seventh surface are as shown in FIG. Further, the transmittance characteristics on the optical axis of the entire optical system of Example 5 are as shown in FIG.

  As shown in FIG. 12, in this embodiment, a desired wavelength characteristic can be obtained by favorably cutting infrared rays.

Table 12
──────────────────
Number of layers Film material Optical film thickness ──────────────────
1 TiO ₂ 0.16 × λ / 4
2 SiO ₂ 0.3227 × λ / 4
3 TiO ₂ 1.7027 × λ / 4
4 SiO ₂ 1.6784 × λ / 4
5 TiO ₂ 1.512 × λ / 4
6 SiO ₂ 1.592 × λ / 4
7 TiO ₂ 1.4907 × λ / 4
8 SiO ₂ 1.5923 × λ / 4
9 TiO ₂ 1.539 × λ / 4
10 SiO ₂ 1.6504 × λ / 4
11 TiO ₂ 1.7057 × λ / 4
12 SiO ₂ 1.8937 × λ / 4
13 TiO ₂ 1.95 × λ / 4
14 SiO ₂ 1.9611 × λ / 4
15 TiO ₂ 1.9477 × λ / 4
16 SiO ₂ 1.9599 × λ / 4
17 TiO ₂ 1.8952 × λ / 4
18 SiO ₂ 0.9414 × λ / 4
──────────────────
Note) λ = 500nm
.

Table 13
─────────────────
Surface Incident angle (°) ─────────────────
r ₁ 32.8
r ₂ 32.8
r ₃ 26.1
r ₄ 50.2
r ₅ 15.6 (IR coat)
r ₆ 37.0
r ₇ 7.9 (IR coat)
─────────────────
.

Table 14
──────────────────
Surface Incident angle average value (°) ──────────────────
IR coated surface 36.5
IR coated surface 11.7
──────────────────
.

Hereinafter, numerical data of each embodiment described above, but the symbols are outside the above, f is the focal length, F _NO is the F-number, 2 [omega is field angle, WE denotes a wide angle end, ST intermediate state, TE is The telephoto end, r ₁ , r ₂ ... Is the radius of curvature of each lens surface, d ₁ , d ₂ ... _Are the distances between the lens surfaces, n _d1 , n _d2 are the refractive index of the d-line of each lens, ν _d1 , ν _d2 ... is the Abbe number of each lens. The aspherical shape is represented by the following formula, where x is an optical axis with the light traveling direction being positive, and y is a direction orthogonal to the optical axis.

x = (y ² / r) / [1+ {1- (K + 1) (y / r) ² } ^1/2 ]
+ A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸
Here, r is a radius of curvature on the optical axis, K is a conical coefficient, and A ₄ , A ₆ , and A ₈ are fourth-order, sixth-order, and eighth-order aspherical coefficients, respectively.

Example 1 and Example 2
r ₁ = -7.898 (aspherical surface) d ₁ = 0.67 n _d1 = 1.52542 ν _d1 = 55.78
r ₂ = 6.245 (aspherical surface) d ₂ = (variable)
r ₃ = ∞ (aperture) d ₃ = 0.75
r ₄ = 2.581 (aspherical surface) d ₄ = 1.40 n _d2 = 1.52542 ν _d2 = 55.78
r ₅ = -3.679 (aspherical surface) d ₅ = 1.02
r ₆ = -8.795 d ₆ = 0.99 n _d3 = 1.60687 ν _d3 = 27.03
r ₇ = 3.222 (aspherical surface) d ₇ = (variable)
r ₈ = 19.576 d ₈ = 0.88 n _d4 = 1.52542 ν _d4 = 55.78
r ₉ = -7.913 (aspherical surface) d ₉ = 1.40
r ₁₀ = ∞ d ₁₀ = 0.50 n _d5 = 1.51633 ν _d5 = 64.14
r ₁₁ = ∞
Aspheric coefficient 1st surface K = 0.000
A ₄ = -4.4963 × 10 ^-3
A ₆ = 1.1928 × 10 ^-3
A ₈ = -6.1456 × 10 ^-5
Second side K = 0.000
A ₄ = -5.9954 × 10 ^-3
A ₆ = 1.8182 × 10 ^-3
A ₈ = 5.4713 × 10 ^-6
4th surface K = -1.9920
A ₄ = 6.8196 × 10 ^-3
A ₆ = -4.6381 × 10 ^-4
A ₈ = 0
Fifth side K = 0.000
A ₄ = 1.1181 × 10 ^-2
A ₆ = -1.2020 × 10 ^-3
A ₈ = 8.4288 × 10 ^-5
Surface 7 K = 3.1471
A ₄ = -1.3938 × 10 ^-2
A ₆ = 4.6177 × 10 ^-3
A ₈ = -1.5879 × 10 ^-3
9th page K = -0.7915
A ₄ = 6.5630 × 10 ^-3
A ₆ = -1.1630 × 10 ^-3
A ₈ = 7.0550 × 10 ^-5
Zoom data (∞)
WE ST TE
f (mm) 3.219 5.073 8.487
F _NO 2.80 3.52 4.84
2ω (°) 76.2 49.4 28.8
d ₂ 5.83321 3.29698 1.52569
d ₇ 0.65023 2.25107 5.19828.

Example 3 and Example 4
r ₁ = -9.540 (aspherical surface) d ₁ = 0.50 n _d1 = 1.52542 ν _d1 = 55.80
r ₂ = 7.264 (aspherical surface) d ₂ = (variable)
r ₃ = ∞ (aperture) d ₃ = 0.30
r ₄ = 2.328 (aspherical surface) d ₄ = 1.11 n _d2 = 1.48749 ν _d2 = 70.23
r ₅ = -3.540 (aspherical surface) d ₅ = 1.65
r ₆ = -7.568 d ₆ = 0.50 n _d3 = 1.60686 ν _d3 = 27.04
r ₇ = 2.371 (aspherical surface) d ₇ = (variable)
r ₈ = -80.915 d ₈ = 1.45 n _d4 = 1.52542 ν _d4 = 55.80
r ₉ = -2.771 (aspherical surface) d ₉ = 0.35
r ₁₀ = ∞ d ₁₀ = 0.50 n _d5 = 1.51633 ν _d5 = 64.14
r ₁₁ = ∞
Aspheric coefficient 1st surface K = 0.000
A ₄ = -1.9086 × 10 ^-2
A ₆ = 4.9653 × 10 ^-3
A ₈ = -3.5838 × 10 ^-4
Second side K = 0.000
A ₄ = -2.0726 × 10 ^-2
A ₆ = 5.9923 × 10 ^-3
A ₈ = -3.1807 × 10 ^-4
4th surface K = -1.9712
A ₄ = 7.5983 × 10 ^-3
A ₆ = -8.6524 × 10 ^-4
A ₈ = 0
Fifth side K = 0.000
A ₄ = 1.1441 × 10 ^-2
A ₆ = -1.5539 × 10 ^-3
A ₈ = 1.0720 × 10 ^-4
Surface 7 K = 2.1787
A ₄ = -1.7149 × 10 ^-2
A ₆ = 4.6266 × 10 ^-3
A ₈ = -8.1781 × 10 ^-3
Surface 9 K = -5.2351
A ₄ = -2.1273 × 10 ^-3
A ₆ = -1.1166 × 10 ^-3
A ₈ = 8.9849 × 10 ^-5
Zoom data (∞)
WE ST TE
f (mm) 3.700 4.971 10.115
F _NO 2.80 3.30 5.28
2ω (°) 65.6 47.4 24.6
d ₂ 5.55135 3.83147 1.28395
d ₇ 0.89118 1.73424 5.14757.

Example 5
r ₁ = ∞ (aperture) d ₁ = 0.10
r ₂ = 1.365 (aspherical surface) d ₂ = 0.63 n _d1 = 1.50913 ν _d1 = 56.20
r ₃ = 2.622 d ₃ = 0.46
r ₄ = 2.750 d ₄ = 0.70 n _d2 = 1.50913 ν _d2 = 56.20
r ₅ = -47.775 (aspherical surface) d ₅ = 0.60
r ₆ = -5.474 (aspherical surface) d ₆ = 0.62 n _d3 = 1.57268 ν _d3 = 33.51
r ₇ = 2.645 (aspherical surface) d ₇ = 0.40
r ₈ = ∞ d ₈ = 0.50 n _d4 = 1.51633 ν _d4 = 64.14
r ₉ = ∞
Aspheric coefficient 2nd surface K = -0.664
A ₄ = 7.93801 × 10 ^-3
A ₆ = 1.59402 × 10 ^-2
A ₈ = -2.69710 × 10 ^-3
Fifth side K = 612.567
A ₄ = -2.69780 × 10 ^-2
A ₆ = -1.22057 × 10 ^-2
A ₈ = 4.19450 × 10 ^-2
6th surface K = -43.850
A ₄ = -4.22561 × 10 ^-1
A ₆ = -5.25463 × 10 ^-2
A ₈ = -7.90009 × 10 ^-2
Surface 7 K = 0.000
A ₄ = -2.59494 × 10 ^-1
A ₆ = 5.15201 × 10 ^-2
A ₈ = −4.92327 × 10 ⁻³ .

  Aberration diagrams showing spherical aberration, astigmatism, and distortion aberration when focusing on infinity in Examples 1 to 5 are shown in FIGS. 13 and 14, (a) shows the state at the wide-angle end, (b) shows the intermediate state, and (c) shows the state at the telephoto end. In these aberration diagrams, “FIY” indicates the image height.

  Examples of the plastic material used for the optical system in the above examples include acrylic resins, cycloolefin resins, polycarbonate resins, and amorphous polyester copolymer resins. From the viewpoint of hygroscopicity, cycloolefin resins And polycarbonate resins are particularly preferred.

  Examples of the cycloolefin-based resin include ZEONEX (R) 480R and ZEONEX (R) 330R, and examples of the polycarbonate-based resin include Panlite (R) and Iupilon (R). Here, (R) is a product name.

  According to the optical system of Example 1, a desired wavelength characteristic is satisfactorily obtained by applying 44 layers of infrared cut coat on one surface. Further, in Example 1, since all the lens members are made of plastic, the entire optical system can be reduced in weight, which is effective for reducing the weight and size of an imaging apparatus using the same.

  In this case, for example, in the process of coating by vacuum deposition, when the coating operation is performed with care so that the temperature of the plastic material does not rise due to the radiant heat generated from the plasma or the evaporation source to reach the thermal deformation temperature. Good.

  According to the optical system of Example 2, 22 layers of infrared cut coat are applied to each of the two lens surfaces to obtain desired wavelength characteristics. In other words, since the number of layers (number of films) on one lens surface may be about half that of an optical system in which only one surface is provided with an infrared cut coat, variations in film thickness of each infrared cut coat can be reduced. As a result, the occurrence of defective products can be reduced, which is effective in improving the yield and cost.

  In particular, when an infrared cut coat is applied to a plastic lens, if the number of layers on one lens surface is small, the time required for the coating process can be shortened, and the temperature rise of the lens in the coating process can be suppressed. . As a result, it is possible to prevent the plastic lens from being deformed due to a temperature rise, and it is difficult for the imaging performance to be lowered due to the deterioration of surface accuracy.

  In Example 1 and Example 2, since all the lens members are made of plastic, the entire optical system can be reduced in weight, which is effective for reducing the weight and size of an imaging device using the same. Furthermore, since the plastic lens can be manufactured at a lower cost than the glass lens, the manufacturing cost of the optical system product, the image pickup apparatus, and the like can be suppressed. Further, since plastic is easier to mold than glass, it is possible to easily manufacture a lens having a desired shape.

  Generally, a plastic lens is manufactured by injection molding of a plastic material. The injection molding is a method in which a plastic fluidized by heating is injected into a mold.

  By using this method, it is possible to keep the cost per lens low compared to the case of manufacturing a lens by glass polishing or glass molding. As a result, the cost of the optical system can be kept low.

  Further, according to the optical system of Example 3, six layers of infrared cut coat are applied to each of the four lens surfaces to obtain desired wavelength characteristics. That is, the number of layers (number of films) on one lens surface may be less than or equal to half that of an optical system in which only one surface is provided with an infrared cut coat, so that variations in film thickness of each infrared cut coat can be further reduced. . As a result, the occurrence of defective products can be reduced, which is effective in improving the yield and cost.

  Furthermore, by reducing the number of layers on one lens surface, the time required for the coating process can be further shortened. Thereby, the deformation of the plastic lens due to the temperature rise can be effectively prevented, and the imaging performance is hardly deteriorated due to the deterioration of the surface accuracy.

  Further, according to the optical system of Example 4, 22 layers of infrared cut coat are applied to the fourth surface, and 8 layers of infrared cut coat are applied to the ninth surface to obtain desired wavelength characteristics. That is, the number of layers (number of films) on one lens surface may be less than or equal to half that of an optical system in which only one surface is provided with an infrared cut coat, so that variations in film thickness of each infrared cut coat can be further reduced. . As a result, the occurrence of defective products can be reduced, which is effective in improving the yield and cost.

  Furthermore, by reducing the number of layers on one lens surface, the time required for the coating process can be further shortened. Thereby, the deformation of the plastic lens due to the temperature rise can be effectively prevented, and the imaging performance is hardly deteriorated due to the deterioration of the surface accuracy.

  The optical system in Example 4 has at least one glass lens and at least one plastic lens, and applies an infrared cut coat to at least one surface of the glass lens and red on at least one surface of the plastic lens. The outer cut coat is applied, and the number of infrared cut coat layers applied to the glass lens is larger than the number of infrared cut coat layers applied to the plastic lens.

  In this way, by including a heat-resistant glass lens in the optical system, the number of infrared cut coat layers in the plastic lens can be reduced, so that deformation of the plastic lens due to temperature rise during the coating process can be reduced. It becomes possible to prevent.

  Usually, the plastic material has a thermal deformation temperature of around 120 ° C, which is lower than the glass lens or glass filter used in the imaging system. Therefore, if the plastic material is coated in the same way as the glass lens or glass filter, no heat is applied. Even in the environment, the temperature of the plastic material is gradually increased by the radiant heat generated from the plasma or the evaporation source to reach the heat deformation temperature, and the shape may change while the multilayer is formed.

  However, as in this embodiment, by reducing the number of layers of the coating film on the plastic lens surface, it is possible to complete the deposition before reaching the heat deformation temperature, thereby preventing the shape change during the deposition. it can.

  According to the optical system of Example 5, as in Examples 1 and 2, all the lens members are made of plastic, and infrared light can be cut well even with a small number of lenses. Therefore, it is effective for reducing the weight and size of an imaging apparatus using a single focus lens.

  As mentioned above, although Example 1-5 was demonstrated, this invention is not limited to the said Example, A various deformation | transformation in the range which does not deviate from the summary is possible.

  For example, in the above embodiment, infrared cut coating is performed by vacuum deposition, but the present invention is not limited to this, and coating may be performed by sputtering.

  In particular, when an infrared cut coat is applied to a plastic lens surface, it is desirable to use a magnetron sputtering method or an ion beam sputtering method that does not evaporate the vapor deposition material by heating. The magnetron sputtering method is a method of knocking out a material by ions confined by the magnetron on the material, and it is desirable to arrange the position of the substrate at a distance not exposed to the plasma generated on the material. In addition, the ion beam sputtering method is a method in which a material is knocked out by an ion beam and a material is deposited on the substrate, and the substrate is not directly exposed to the ion beam. It is possible to form a film with By such a technique, an increase in the temperature of the plastic lens can be suppressed, and a change in shape can be prevented.

  By the way, on the image pickup surface I of the CCD, as shown in FIG. 16, a complementary color mosaic filter is provided in which four color filters of cyan, magenta, yellow, and green are provided in a mosaic pattern corresponding to the image pickup pixels. ing. These four types of color filters are arranged in a mosaic so that each of them has approximately the same number and adjacent pixels do not correspond to the same type of color filter. Thereby, more faithful color reproduction becomes possible.

  Specifically, the complementary color mosaic filter is composed of at least four types of color filters as shown in FIG. 16, and the characteristics of the four types of color filters are preferably as follows.

The green color filter G has a spectral intensity peak at the wavelength _GP ,
Yellow filter element Y _e has a spectral strength peak at a wavelength Y _P,
Each cyan filter element C has a spectral strength peak at a wavelength C _P,
The magenta color filter M has peaks at wavelengths M _P1 and M _P2 and satisfies the following conditions.

510 nm <G _P <540 nm
5 nm <Y _P −G _P <35 nm
−100 nm <C _P −G _P <−5 nm
430 nm <M _P1 <480 nm
580 nm <M _P2 <640 nm
Further, the green, yellow, and cyan color filters have an intensity of 80% or more at a wavelength of 530 nm with respect to each spectral intensity peak, and the magenta color filter has an intensity of 10% at a wavelength of 530 nm. From the viewpoint of improving the color reproducibility, it is more preferable that the strength is 50% to 50%.

FIG. 17 shows an example of each wavelength characteristic in each of the above embodiments. The green color filter G has a spectral intensity beak at 525 nm. The yellow color filter Y _e has a spectral intensity peak at 555 nm. The cyan color filter C has a spectral intensity peak at 510 nm. The magenta color filter M has peaks at 445 nm and 620 nm. In each color filter at 530 nm, G is 99%, _Ye is 95%, C is 97%, and M is 38% with respect to the respective spectral intensity peaks.

In the case of such a complementary color filter, the following signal processing is performed electrically with a controller (not shown) (or a controller used in a digital camera),
Luminance signal Y = | G + M + Y _e + C | × 1/4
Color signal R−Y = | (M + Y _e ) − (G + C) |
B−Y = | (M + C) − (G + Y _e ) |
The signal is converted into R (red), G (green), and B (blue) signals.

  In the image pickup apparatus of the present invention, for adjusting the light amount, a variable aperture may be used in which the brightness stop S is configured with a plurality of aperture blades and the aperture shape is variable. FIG. 18 is an explanatory diagram illustrating an example of the aperture shape at the time of opening, and FIG. 19 is an explanatory diagram illustrating an example of the aperture shape at the time of two-stage aperture. 18 and 19, OP indicates the optical axis, Da indicates six diaphragm plates, and Xa and Xb indicate openings. In the present invention, the aperture shape of the aperture can be set to only two types, that is, an open state (FIG. 18) and an aperture value (a two-stage aperture, FIG. 19) having an F value that satisfies a predetermined condition.

  Or, using a turret provided with a plurality of fixed-shaped brightness stops with different shapes or transmittances, depending on the required brightness, place any brightness stop on the object-side optical axis of the imaging optical system. With the arrangement, the diaphragm mechanism can be thinned. In addition, a configuration in which a light amount reduction filter having a transmittance lower than the transmittance of other aperture stops is arranged in the aperture that reduces the amount of light most among the apertures of the aperture stops arranged on the turret. Good. Accordingly, the aperture diameter of the diaphragm is not excessively narrowed, and deterioration of the imaging performance due to diffraction that occurs due to the small aperture diameter of the diaphragm can be suppressed.

  FIG. 20 is a perspective view showing an example of the configuration in this case. The brightness of the 0th, −1, −2, −3, and −4 stages is adjusted to the position of the stop S on the optical axis on the object side of the first positive lens L1 of the imaging lens system of Embodiment 4. The turret 10 that enables the above is disposed.

  The turret 10 has an opening 1A (a transmittance of 100% for a wavelength of 550 nm) having a circular aperture with a maximum aperture diameter and a fixed aperture of 0 stage, and an opening of the opening 1A for -1 stage correction. An opening 1B made of a transparent parallel plate having a fixed opening shape having an opening area that is about half the area (the transmittance for the wavelength of 550 nm is 99%), a circular opening having the same area as the opening 1B, and −2 steps In order to correct to -3 and -4 stages, apertures 1C, 1D, and 1E provided with ND filters having transmittances of 50%, 25%, and 13% for a wavelength of 550 nm, respectively, are provided.

  The light quantity is adjusted by arranging one of the apertures at the aperture position by turning around the rotation shaft 11 provided in the turret 10.

  Moreover, it can replace with the turret 10 shown in FIG. 20, and the turret 10 'shown in the front view of FIG. 21 can be used. Brightness can be adjusted in 0, −1, −2, −3, and −4 positions at the position of the stop S on the optical axis on the object side of the first positive lens L1 of the imaging lens system. A turret 10 'is arranged.

  The turret 10 ′ has an opening shape for adjusting the zero stage having a circular and fixed opening 1 A ′ having a maximum aperture diameter, and an opening area that is about half of the opening area of the opening 1 A ′ for −1 stage correction. The opening 1B ′ having a fixed opening shape and the opening areas 1C ′, 1D ′, and 1E ′ having fixed shapes for the correction to the −2 step, the −3 step, and the −4 step are further reduced in order. Have.

  The light quantity is adjusted by arranging any opening at the stop position by turning around the rotation shaft 11 provided in the turret 10 '.

  In order to reduce the thickness, the aperture of the aperture stop S may be an aperture having a fixed shape and position, and the light amount adjustment may be performed by electrically adjusting an output signal from the image sensor. Alternatively, the light amount may be adjusted by inserting and removing an ND filter between other spaces in the lens system, for example, the third negative lens L3 and the CCD cover glass CG. FIG. 22 is a diagram showing an example of this. The opening 1A ″ of the turret 10 ″ is a through surface or hollow opening, the opening 1B ″ is an ND filter having a transmittance of 1/2, and the opening 1C ″ is a transmittance of 1/4. The ND filter, aperture 1D ″ is a turret-shaped filter provided with an ND filter having a transmittance of 1/8, and any aperture is arranged at any position in the optical path by rotation around the central rotation axis. To adjust the light intensity.

  Further, as a filter for adjusting the light amount, a filter surface capable of adjusting the light amount so as to suppress unevenness in the light amount may be provided. For example, as shown in FIG. 23, the light intensity is centered concentrically so that the transmittance is uniform with priority given to the light intensity at the center for dark subjects and the brightness unevenness is compensated only for bright subjects. It is good also as a structure which arrange | positions the filter which falls so much.

  Further, as the diaphragm S, the peripheral portion on the incident surface side of the first positive lens L1 may be painted black.

  When the imaging apparatus according to the present invention stores an image as a still image like a camera or the like, a shutter for adjusting the amount of light may be disposed in the optical path.

  As such a shutter, a focal plane shutter, a rotary shutter, or a liquid crystal shutter disposed immediately before the CCD may be used, or the aperture stop itself may be configured as a shutter.

  FIG. 24 shows an example of the shutter. FIG. 24 shows an example of a rotary focal plane shutter which is one of the focal plane shutters. FIG. 24 (a) is a view seen from the back side, and FIG. 24 (b) is a view seen from the front side. is there. A shutter substrate 15 is arranged immediately before the image plane or at an arbitrary optical path position. The substrate 15 is provided with an opening 16 that transmits an effective light beam of the optical system. Reference numeral 17 denotes a rotary shutter curtain. Reference numeral 18 denotes a rotary shaft of the rotary shutter curtain 17. The rotary shaft 18 rotates with respect to the substrate 15 and is integrated with the rotary shutter curtain 17. The rotating shaft 18 is connected to gears 19 and 20 on the surface of the substrate 15. The gears 19 and 20 are connected to a motor (not shown).

  In such a configuration, the rotary shutter curtain 17 is configured to rotate about the rotation shaft 18 via the gears 19 and 20 and the rotation shaft 18 by driving a motor (not shown).

  The rotary shutter curtain 17 is formed in a substantially semicircular shape and shields and retreats the opening 16 of the substrate 15 by rotation, thereby serving as a shutter. The shutter speed is adjusted by changing the rotating speed of the rotary shutter curtain 17.

  FIGS. 25A to 25D are views of the rotary shutter curtain 17 rotating from the image plane side. It moves in the order of (a), (b), (c), (d), and (a) in the figure with time.

  As described above, the aperture stop S with a fixed shape and a filter or shutter that adjusts the amount of light are placed at different positions in the lens system. In addition, an imaging apparatus capable of reducing the overall length of the lens system can be obtained.

  Further, a configuration may be adopted in which electrical control is performed so as to obtain a still image by extracting a part of the electrical signal of the CCD without using a mechanical shutter. An example of such a configuration will be described with reference to FIGS. FIG. 26 is a diagram for explaining the operation of CCD imaging in which signals are sequentially read out by an interlace method (interlaced scanning method). In FIG. 26, Pa to Pc are photosensitive sections using photodiodes, Va to Vc are vertical transfer sections using CCD, and Ha is a horizontal transfer section using CCD. The A field indicates an odd field, and the B field indicates an even field.

  In the configuration of FIG. 26, the basic operation is performed as follows. That is, (1) signal charge accumulation (photoelectric conversion) by light in the photosensitive part, (2) signal charge shift (field shift) from the photosensitive part to the vertical transfer part, and (3) signal charge in the vertical transfer part. Transfer (vertical transfer), (4) transfer of signal charges from the vertical transfer unit to the horizontal transfer unit (line shift), (5) transfer of signal charges in the horizontal transfer unit (horizontal transfer), (6) horizontal transfer unit The signal charge is detected (detected) at the output terminal. Such sequential reading can be performed using either the A field (odd field) or the B field (even field).

  In the interlaced (interlaced scanning) CCD imaging of FIG. 26, the accumulation timing of the A field and the B field is shifted by 1/60 in the TV broadcast system and the analog video system. If this is used as it is as a DSC (Digital Spectral Compatible) image to form a frame image, in the case of a moving subject, a blur like a double image occurs. Therefore, in this type of CCD imaging, the A and B fields are simultaneously exposed to mix the signals of adjacent fields. Then, after a fluorescent light is emitted at the end of exposure using a mechanical shutter, a method is employed in which the A field and the B field are read out separately to synthesize signals.

  In the present invention, the mechanical shutter functions only for smear prevention and only the A field is sequentially read out, or the A and B fields are simultaneously mixed readout. The high-speed shutter can be released regardless of the shutter speed (because it can be controlled only with an electronic shutter). In the example of FIG. 26, since the number of CCDs in the vertical transfer unit is half of the number of photodiodes constituting the photosensitive unit, there is an advantage that it is easy to reduce the size.

  FIG. 27 is a diagram for explaining the operation of CCD imaging in which sequential readout of signals is performed in a progressive manner. In FIG. 27, Pd to Pf are photosensitive portions using photodiodes, Vd to Vf are vertical transfer portions by CCD, and Hb is a horizontal transfer portion by CCD.

  In FIG. 27, since reading can be performed in the pixel arrangement order, it is possible to electronically control all charge accumulation and reading operations. Therefore, the exposure time can be shortened to about (1/10000 seconds). In the example of FIG. 27, the number of vertical CCDs is larger than in the case of FIG. 26, and there is a disadvantage that downsizing is difficult. However, because of the advantages as described above, in the present invention, FIG. Any of these methods can be employed.

  The imaging device of the present invention as described above is an imaging device that forms an object image with an imaging lens system and receives the image with an imaging element such as a CCD, and in particular, a digital camera, video camera, information processing It can be used for personal computers, telephones, and especially mobile phones that are convenient to carry. The embodiment is illustrated below.

  28 to 30 are conceptual diagrams of a configuration in which the optical system according to the present invention is incorporated in a photographing optical system 41 of a digital camera. 28 is a front perspective view showing the appearance of the digital camera 40, FIG. 29 is a rear front view thereof, and FIG. 30 is a schematic perspective plan view showing the configuration of the digital camera 40. However, in FIGS. 28 and 30, the photographing optical system 41 is not retracted. In this example, the digital camera 40 includes a photographing optical system 41 having a photographing optical path 42, a finder optical system 43 having a finder optical path 44, a shutter 45, a flash 46, a liquid crystal display monitor 47, a focal length change button 61, a setting. When the photographing optical system 41 is retracted, including the change switch 62, the photographing optical system 41, the finder optical system 43 and the flash 46 are covered with the cover 60 by sliding the cover 60. When the cover 60 is opened and the camera 40 is set to the photographing state, the photographing optical system 41 enters the non-collapsed state shown in FIG. 30. When the shutter 45 disposed on the upper part of the camera 40 is pressed, the photographing optical system is linked. Photographing is performed through the system 41, for example, the zoom lens system of the first embodiment. An object image formed by the photographing optical system 41 is formed on the imaging surface of the CCD 49 via a low-pass filter LF and a cover glass CG. The object image received by the CCD 49 is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera via the processing means 51. Further, the processing means 51 is connected to a recording means 52 so that a photographed electronic image can be recorded. The recording means 52 may be provided separately from the processing means 51, or may be configured to perform recording / writing electronically using a floppy disk, memory card, MO, or the like. Further, it may be configured as a silver salt camera in which a silver salt film is arranged in place of the CCD 49.

  Further, a finder objective optical system 53 is disposed on the finder optical path 44. The finder objective optical system 53 includes a plurality of lens groups (three groups in the figure) and two prisms, and includes a zoom optical system in which the focal length changes in conjunction with the zoom lens system of the photographing optical system 41. The object image formed by the finder objective optical system 53 is formed on the field frame 57 of the erecting prism 55 which is an image erecting member. Behind the erecting prism 55, an eyepiece optical system 59 for guiding the erect image to the observer eyeball E is disposed. A cover member 50 is disposed on the exit side of the eyepiece optical system 59.

  In the digital camera 40 configured in this manner, the photographing optical system 41 has a high performance and a small size and can be retracted, so that a high performance and a small size can be realized.

  Next, a personal computer as an example of an information processing apparatus in which the optical system of the present invention is incorporated as an objective optical system is shown in FIGS. 31 is a front perspective view with the cover of the personal computer 300 opened, FIG. 32 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 33 is a side view of the state of FIG. As shown in FIGS. 31 to 33, a personal computer 300 includes a keyboard 301 for a writer to input information from the outside, information processing means and recording means not shown, and a monitor for displaying information to the operator. 302 and a photographing optical system 303 for photographing the operator himself and surrounding images. Here, the monitor 302 may be a transmissive liquid crystal display element that is illuminated from the back by a backlight (not shown), a reflective liquid crystal display element that reflects and displays light from the front, a CRT display, or the like. Further, in the drawing, the photographing optical system 303 is built in the upper right of the monitor 302. However, the imaging optical system 303 is not limited to the place, and may be anywhere around the monitor 302 or the keyboard 301.

  The photographing optical system 303 has an objective lens 112 including an optical system according to the present invention (abbreviated in the drawing) and an image sensor chip 162 that receives an image on a photographing optical path 304. These are built in the personal computer 300.

  Here, a cover glass CG having a low-pass filter function is additionally attached on the image pickup element chip 162 to be integrally formed as an image pickup unit 160, and can be touched at the rear end of the lens frame 113 of the objective lens 112 with one touch. Since it can be fitted and attached, it is not necessary to align the center of the objective lens 112 and the image pickup element chip 162 and to adjust the surface interval, and the assembly is simplified. A cover glass 114 for protecting the objective lens 112 is disposed at the tip of the lens frame 113.

  The object image received by the image sensor chip 162 is input to the processing means of the personal computer 300 via the terminal 166 and displayed on the monitor 302 as an electronic image. FIG. A captured image 305 is shown. The image 305 can also be displayed on the personal computer of the communication partner from a remote location via the processing means, the Internet, or the telephone.

  Next, FIG. 34 shows a telephone which is an example of an information processing apparatus in which the optical system of the present invention is incorporated as a photographing optical system, particularly a portable telephone which is convenient to carry. 34A is a front view of the mobile phone 400, FIG. 34B is a side view, and FIG. 34C is a cross-sectional view of the photographing optical system 405. As shown in FIGS. 34A to 34C, the mobile phone 400 includes a microphone unit 401 that inputs the voice of the operator as information, a speaker unit 402 that outputs the voice of the other party, and an operator who receives information. An input dial 403 for inputting information, a monitor 404 for displaying information such as a photographed image and a telephone number of the operator and the other party, a photographing optical system 405, an antenna 406 for transmitting and receiving communication radio waves, and an image And processing means (not shown) for processing information, communication information, input signals, and the like. Here, the monitor 404 is a liquid crystal display element. In the drawing, the arrangement positions of the respective components are not particularly limited to these. The photographing optical system 405 includes an objective lens 112 including an optical system (abbreviated in the drawing) according to the present invention disposed on a photographing optical path 407, and an image sensor chip 162 that receives an object image. These are built in the mobile phone 400.

  Here, a cover glass CG having a low-pass filter function is additionally attached on the image pickup element chip 162 to be integrally formed as an image pickup unit 160, and can be touched at the rear end of the lens frame 113 of the objective lens 112 with one touch. Since it can be fitted and attached, it is not necessary to align the center of the objective lens 112 and the image pickup element chip 162 and to adjust the surface interval, and the assembly is simplified. A cover glass 114 for protecting the objective lens 112 is disposed at the tip of the lens frame 113.

  The object image received by the imaging element chip 162 is input to the processing means (not shown) via the terminal 166 and displayed as an electronic image on the monitor 404, the monitor of the communication partner, or both. . Further, when transmitting an image to a communication partner, the processing means includes a signal processing function for converting information of an object image received by the image sensor chip 162 into a signal that can be transmitted.

FIG. 2 is a lens cross-sectional view of the zoom lens system of Example 1 used in the present invention at a wide-angle end (a), an intermediate state (b), and a telephoto end (c) when focusing on an object point at infinity. FIG. 6 is a lens cross-sectional view of the zoom lens system of Example 3 used in the present invention at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity. It is a lens sectional view at the time of infinity object point focusing of the imaging lens system of Example 5 used for the present invention. FIG. 6 is a diagram showing transmittance characteristics on the optical axis of the entire optical system of Example 1. FIG. 10 is a diagram illustrating transmittance characteristics on any one of an eighth surface and a ninth surface of the zoom lens system according to Example 2; It is a figure which shows the transmittance | permeability characteristic on the optical axis by the infrared cut coat of the 2nd surface of the 8th surface of the zoom lens system of Example 2, and a 9th surface. FIG. 10 is a diagram illustrating transmittance characteristics on any one of a fourth surface, a sixth surface, an eighth surface, and a ninth surface of the zoom lens system according to Example 3; FIG. 6 is a diagram showing transmittance characteristics on the optical axis of the entire optical system of Example 3. It is a figure which shows the transmittance | permeability characteristic on the optical axis by the infrared cut coat of the 4th surface of the zoom lens system of Example 4. It is a figure which shows the transmittance | permeability characteristic on the optical axis by the infrared cut coat of the 9th surface of the zoom lens system of Example 4. FIG. 10 is a diagram showing a transmittance characteristic on any one of a fifth surface and a seventh surface of the optical system of Example 5. FIG. 10 is a diagram showing transmittance characteristics on the optical axis of the entire optical system of Example 5. FIG. 6 is an aberration diagram illustrating spherical aberration, astigmatism, and distortion at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on infinity according to Example 1. FIG. 10 is an aberration diagram illustrating spherical aberration, astigmatism, and distortion at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on infinity according to Example 3. FIG. 6 is an aberration diagram showing spherical aberration, astigmatism, and distortion aberration when focusing on infinity in Example 5. It is a figure which shows the color filter arrangement | positioning of a complementary color mosaic filter. It is a figure which shows an example of the wavelength characteristic of a complementary color mosaic filter. It is a figure which shows having opened the aperture shape of the aperture_diaphragm | restriction. It is a figure which shows the state which made the aperture shape of an aperture_diaphragm | restriction 2 steps | paragraphs. It is a perspective view which shows the structure of the imaging optical system of this invention which has arrange | positioned the turret which provided the several aperture stop of the shape fixation from which a shape differs in the transmittance | permeability. It is a front view which shows another turret instead of the turret shown in FIG. It is a figure which shows another turret-shaped light quantity adjustment filter which can be utilized in this invention. It is a figure which shows the example of the filter which suppresses light quantity nonuniformity. It is the back view and front view which show the example of a rotary focal plane shutter. It is a figure which shows a mode that the rotary shutter curtain of the shutter of FIG. 24 rotates. It is operation | movement explanatory drawing of interlace type CCD imaging. It is operation | movement explanatory drawing of progressive CCD imaging. It is a conceptual diagram of the structure which incorporated the optical system by this invention in the imaging optical system of a digital camera. FIG. 29 is a rear perspective view of the digital camera of FIG. 28. It is sectional drawing of the digital camera of FIG. It is the front perspective view which opened the cover of the personal computer in which the optical system by this invention was integrated as an objective optical system. It is sectional drawing of the imaging optical system of a personal computer. It is a side view of the state of FIG. 1 is a front view, a side view, and a sectional view of a photographing optical system of a mobile phone in which an optical system according to the present invention is incorporated as an objective optical system.

Explanation of symbols

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group S ... Aperture stop CG ... Cover glass I ... Image plane L11 ... 1st lens group negative lens L21 ... 2nd lens group positive lens L22 ... 2nd Lens group negative lens L31 ... Third lens group positive lens L1 ... First positive lens L2 ... Second positive lens L3 ... Third negative lens OP ... Optical axis Da ... Diaphragm plate Xa, Xb ... Openings Pa to Pf ... Photosensitive part Va to Vf: vertical transfer unit Ha, Hb: horizontal transfer unit E ... observer eyeball LF ... low pass filter 1A, 1B, 1C, 1D, 1E ... aperture 1A ', 1B', 1C ', 1D', 1E '... aperture 1A ", 1B", 1C ", 1D" ... opening 10 ... turret 10 '... turret 10 "... turret 11 ... rotating shaft 15 ... shutter substrate 16 ... opening 17 ... rotary shutter curtain 18 ... rotating shaft 19, 20 ... gear 40 ... Desi Tal camera 41 ... Shooting optical system 42 ... Shooting optical path 43 ... Viewfinder optical system 44 ... Viewfinder optical path 45 ... Shutter 46 ... Flash 47 ... Liquid crystal display monitor 49 ... CCD
DESCRIPTION OF SYMBOLS 50 ... Cover member 51 ... Processing means 52 ... Recording means 53 ... Finder objective optical system 55 ... Erect prism 57 ... Field frame 59 ... Eyepiece optical system 60 ... Cover 61 ... Focal length change button 62 ... Setting change switch 112 ... Objective Lens 113 ... Mirror frame 114 ... Cover glass 160 ... Imaging unit 162 ... Imaging element chip 166 ... Terminal 300 ... PC 301 ... Keyboard 302 ... Monitor 303 ... Shooting optical system 304 ... Shooting optical path 305 ... Image 400 ... Mobile phone 401 ... Microphone unit 402 ... Speaker unit 403 ... Input dial 404 ... Monitor 405 ... Shooting optical system 406 ... Antenna 407 ... Shooting optical path

Claims (6)

In an imaging apparatus including an optical system including a plurality of optical elements having finite refractive power, and an electronic imaging element disposed on the image side of the optical system,
At least one of the plurality of optical elements is made of plastic, and an infrared cut coat is applied to at least one surface of the optical element made of plastic. The imaging apparatus according to claim 1, wherein the infrared cut coat is applied to a plurality of refractive surfaces including one surface of the optical element made of plastic. The imaging apparatus according to claim 1, wherein the transmittance of the entire optical system is 10% or less of an average value of transmittance at wavelengths of 500 nm to 550 nm over a wavelength range of 750 nm to 850 nm. In an optical system including an optical element having a finite refractive power,
An optical system, wherein at least one of the plurality of optical elements is made of plastic, and an infrared cut coat is applied to at least one surface of the optical element made of plastic. 5. The optical system according to claim 4, wherein the infrared cut coat is applied to a plurality of refractive surfaces including one surface of the optical element made of the plastic. 6. The optical system according to claim 4, wherein the transmittance of the entire optical system is 10% or less of an average value of transmittance at wavelengths of 500 nm to 550 nm over a wavelength range of 750 nm to 850 nm.

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